Video processing apparatus, video processing method, and medium

ABSTRACT

A camera microcomputer sets a gamma characteristic that suits a luminance input value/output value relationship in the entire luminance region extending from lower luminance to higher luminance of a video signal to a luminance input value/output value relationship of a referential gamma characteristic, irrespective of input dynamic range. A gamma correction processing unit performs gamma correction processing on a captured video signal in such a way as to convert the input value into the output value based on the set gamma characteristic.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a video processing apparatus, a videoprocessing method, and a medium.

Description of the Related Art

In a conventional video processing system including an imaging apparatuscapable of sequentially capturing images of a subject and a displayapparatus capable of displaying a video, both of the imaging apparatusand the display apparatus perform gradation correction processing basedon gamma correction. The gradation correction processing (i.e., gammacorrection processing) performed by the imaging apparatus includesconverting a luminance input code value of a captured video signal intoan output code value corresponding to a gamma characteristic of theimaging apparatus (i.e., a camera gamma). The gradation correctionprocessing (i.e., gamma correction processing) performed by the displayapparatus includes converting a luminance input code value of a suppliedvideo signal into a luminance value based on a gamma characteristic ofthe display apparatus (i.e., a display gamma). Thus, only a limited partof the brightness of a subject having a very wide dynamic range in thereal world can be segmented. It is possible to realize a satisfactorydisplay in a definite narrow dynamic range of a monitor unit of thedisplay apparatus.

Further, as a gradation correction processing technique capable ofsecuring a practical input dynamic range for the imaging apparatus, aconventional technique discussed in Japanese Patent ApplicationLaid-Open No. 2002-223373 widens the input dynamic range by performinggamma correction processing including knee correction.

The above-mentioned gamma correction processing including the kneecorrection is determined by compressing the contrast in both amiddle-luminance region and a high-luminance region while securing thepractical input dynamic range. However, compressing the contrast in themiddle-luminance and high-luminance regions can result in, for example,unnaturalness, in a gradation characteristic of the entire systemincluding the imaging apparatus and the display apparatus because thecontrast in the high-luminance region is relatively compressed comparedto the low-luminance region. More specifically, a gradationcharacteristic of a video displayed by the display apparatus can resultin luminance change reduced in the high-luminance region, compared to agradation characteristic of a real subject. Thus, the video displayed bythe display apparatus is unnatural in that natural gradation, color, andsharpness of the real subject cannot be reproduced.

Meanwhile, there is a conventional gradation correction processingtechnique applicable to the display apparatus, which is capable ofcompensating the compressed contrast in the high-luminance region byincreasing the brightness of the high-luminance region. However, thevideo signal output from the imaging apparatus does not includegradation information about the middle-luminance and high-luminanceregions. Thus, the gradation cannot be sufficiently restored by only theprocessing performed by the display apparatus. Further, since thedisplay apparatus cannot obtain information about the gammacharacteristic of the imaging apparatus, it is difficult for the displayapparatus to reproduce the natural gradation, color, and sharpness ofthe real subject.

SUMMARY OF THE INVENTION

According to exemplary embodiments, a video processing apparatusincludes a control unit configured to set a gamma characteristicgenerated for a second dynamic range larger than a first dynamic range,based on a referential gamma characteristic in which a relationshipbetween a luminance input value and a luminance output value ispredetermined in the entire luminance range of the first dynamic range,without changing the relationship, and a correction unit configured toperform gamma correction processing on a video signal having the seconddynamic range by using the set gamma characteristic.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a schematic configuration of animaging apparatus according to an exemplary embodiment.

FIG. 2 is a perspective view illustrating an overview of the imagingapparatus.

FIGS. 3A, 3B, 3C, and 3D illustrate gamma correction processing in anordinary imaging mode.

FIGS. 4A, 4B, 4C, and 4D illustrate gamma correction processing in ahigh-luminance priority mode.

FIG. 5 is a flowchart illustrating a gradation correction processingcontrol performed by the imaging apparatus.

FIG. 6 is a schematic view illustrating an exemplary exposure displaycontrol performed by the imaging apparatus.

FIG. 7 is a block diagram illustrating a schematic configuration of avideo processing system according to the exemplary embodiment.

FIG. 8 is a flowchart illustrating a peak luminance value settingprocessing control performed by a display apparatus.

FIG. 9 is a flowchart illustrating a gamma correction processing controlperformed by the display apparatus.

FIG. 10 is a flowchart illustrating a signal processing controlperformed by the display apparatus.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an exemplary embodiment of the present invention will bedescribed in detail below with reference to the attached drawings.

<Configuration of Imaging Apparatus>

FIG. 1 is a block diagram illustrating a schematic configuration of animaging apparatus 100, as an example of a video processing apparatusaccording to the present exemplary embodiment.

A lens 101 forms a subject image on an imaging plane of an image sensor105. A diaphragm 102 adjusts a quantity of light entering via the lens101. The image sensor 105 converts the subject image formed on theimaging plane via the lens 101 and the diaphragm 102 into a videosignal. Although not illustrated, an analog/digital (A/D) converter isprovided to process the video signal output from the image sensor 105.Then, the A/D converter obtains a digital video signal by coding ananalog video signal through A/D conversion and transmits the digitalvideo signal to a signal processing unit 112. The lens 101 may has alens shift type camera-shake correction function capable of causing anoptical system dedicated to camera-shake correction to shift in anoptical axis thereof. Further, the camera-shake correction function maybe a sensor shift type correction that changes the position of the imagesensor 105 relative to the optical axis of the lens 101 or may be areading control type correction that performs camera-shake correction bycontrolling reading from the image sensor 105.

The signal processing unit 112 includes a white balance (WB) correctionprocessing unit 107, an edge emphasizing processing unit 108, a gamma(γ) correction processing unit 109, and a luminance/color informationdetection unit 110. The WB correction processing unit 107 performs whitebalance correction processing on the video signal transmitted from theimage sensor 105. The edge emphasizing processing unit 108 performs edgeemphasizing processing on the video signal having been subjected to theWB correction processing. The gamma correction processing unit 109performs gamma correction processing based on a gamma characteristic(i.e., camera gamma) of the imaging apparatus. The gamma correctionprocessing will be described in detail below. The luminance/colorinformation detection unit 110 included in the signal processing unit112 divides one frame image of the video signal into horizontaldirection components and vertical direction components to set aplurality of luminance/color information detection frames (hereinafter,simply referred to as “detection frames”). The luminance/colorinformation detection unit 110 performs processing for integrating pixelvalues in respective detection frames and detects luminance informationand color information of each detection frame of the subject image. Theluminance/color information detection unit 110 transmits the luminanceinformation and the color information of each detection frame detectedby the luminance/color information detection unit 110 to a cameramicrocomputer 111. Although the signal processing unit 112 performsvarious processing, other than the WB correction processing, the edgeemphasizing processing, the gamma correction processing, and theluminance/color information detection processing, description thereof isomitted. The signal processing unit 112 outputs the video signal havingbeen subjected to various signal processing to a display device 116. Thedisplay device 116 displays a video based on the received signal.Further, the signal processing unit 112 can record the processed videosignal to a computer readable storage medium, such as a magnetic tape115, a digital versatile disk (DVD) disk 117, or a memory card 118.

The camera microcomputer 111, which is an example of a control unitprovided in the imaging apparatus 100, calculates respective correctionvalues to be used in the WB correction processing, the edge emphasizingprocessing, and the gamma correction processing based on subjectinformation, such as the luminance information and the color informationdetected by the luminance/color information detection unit 110. Then,the camera microcomputer 111 transmits a correction value to be used inthe WB correction processing to the WB correction processing unit 107.The camera microcomputer 111 transmits a correction value to be used inthe edge emphasizing processing to the edge emphasizing processing unit108. The camera microcomputer 111 transmits a correction value to beused in the gamma correction processing (e.g., a later-described gammacorrection curve of the gamma characteristic) to the gamma correctionprocessing unit 109. In this way, the WB correction processing unit 107,the edge emphasizing processing unit 108, and the gamma correctionprocessing unit 109 perform individual processing based on the suppliedcorrection values, respectively. The camera microcomputer 111 causes animage sensor driving unit 106 to perform a control to store electriccharges in the image sensor 105 and read the stored electric charges.The camera microcomputer 111 causes a lens driving unit 103 to perform acontrol to realize focusing and zooming operations of the lens 101. Thecamera microcomputer 111 can perform an exposure control based on theluminance information and the color information by causing a diaphragmdriving unit 104 to control the diaphragm 102 and causing the imagesensor driving unit 106 to control the shutter speed of the image sensor105. Further, the camera microcomputer 111 can perform a camera-shakecorrection control if the imaging apparatus 100 possesses an appropriate(e.g., lens shift type, sensor shift type, or reading control type)camera-shake correction function.

<Configuration of Video Camera>

FIG. 2 is a perspective view illustrating an overview of a video camera120, which includes the imaging apparatus 100 integrated with thedisplay device 116 according to the present exemplary embodiment, as anexample of a video processing system.

The DVD disk 117, the magnetic tape 115, and the memory card 118 areaccommodated in the video camera 120, so that video signals and stillimages can be recorded and reproduced. A lens unit 121 includes the lens101 and the diaphragm 102 illustrated in FIG. 1. A microphone 122 isequipped to collect sounds during an image capturing operation. Anelectronic view finder (EVF) 123 is equipped to enable a user to confirma captured subject or display a reproduction image. A moving imagetrigger switch 124 is, for example, a push button, which is operablewhen a user transmits a moving image capturing start instruction or amoving image capturing stop instruction to the device. A still imagetrigger switch 125 is, for example, a push button, which is operablewhen a user transmits a still image capturing start instruction or astill image capturing stop instruction to the device. A mode dial 126 isa rotary switch having a plurality of modes, including “reproduction”(i.e., a mode selectable when a user sets a reproduction mode), “camera”(i.e., a mode selectable when a user sets a camera mode), “ordinaryimaging” (i.e., a mode selectable when a user sets an ordinary imagingmode), “high-luminance priority” (i.e., a mode selectable when a usersets a high-luminance priority mode), and “OFF” selectable when a userdoes not set the above-mentioned modes. An operation switch group 127includes an appropriate number of operation switches operable when auser operates the video camera 120, a mode key operable to input animage-quality filter mode, a menu key operable to perform a menuoperation, and a reproduction key operable to perform a reproductionoperation. A liquid crystal panel 128 is flexibly connected to the videocamera 120 so that the liquid crystal panel 128 can be opened or closedrelative to a side surface of the camera body. The liquid crystal panel128 is rotatable in the horizontal direction. Similar to the EVF 123,the liquid crystal panel 128 can be used to confirm a captured subjector display a reproduction image. In the exemplary state illustrated inFIG. 2, the liquid crystal panel 128 is opened relative to the body ofthe video camera 120. The display device 116 illustrated in FIG. 1 canbe used as the EVF 123 or the liquid crystal panel 128. A speaker 129can output sounds and voices recorded together with a video when thevideo is reproduced. A battery 130 is a secondary battery, which cansupply electric power to the video camera 120. The battery 130 isattachable to and detachable from the camera body. In this respect, thevideo camera 120 illustrated in FIG. 2 includes the configurationrequired to capture and record images of a subject, which corresponds tothe imaging apparatus 100 according to the present exemplary embodiment.Further, the video camera 120 includes the configuration required toreproduce captured video signals and recorded video signals to displayimages on the liquid crystal panel 128, which corresponds to the displayapparatus according to the present exemplary embodiment.

<High-Luminance Priority Mode and Ordinary Imaging Mode>

The imaging apparatus 100 according to the present exemplary embodimentincludes, at least, the high-luminance priority mode and the ordinaryimaging mode, as imaging modes, which are selectable in a videocapturing operation. When the imaging mode is the high-luminancepriority mode, the imaging apparatus 100 uses a high-luminance prioritygamma correction curve as the gamma characteristic (i.e., camera gamma)in the gamma correction processing. On the other hand, when the imagingmode is the ordinary imaging mode, the imaging apparatus 100 uses anordinary imaging gamma correction curve. Hereinafter, the gammacharacteristics (i.e., gamma correction curves) to be used by theimaging apparatus 100 according to the present exemplary embodiment, inthe gamma correction processing performed in the ordinary imaging modeand the high-luminance priority mode, will be described.

In the ordinary imaging mode, the imaging apparatus 100 performsgradation correction through the gamma correction processing includingthe knee correction, which can compress the contrast in bothmiddle-luminance and high-luminance regions while securing a practicalinput dynamic range. In the present exemplary embodiment, compressingthe contrast is equivalent to decreasing the gradient of thecharacteristic curve, which can be expressed by a change in luminancerelative to a change in dynamic range.

Hereinafter, gradation correction characteristics in the ordinaryimaging mode will be described in detail below with reference to FIGS.3A to 3D. Each of FIG. 3A and FIG. 3B illustrates the gammacharacteristic (i.e., camera gamma) of the imaging apparatus. FIG. 3Cillustrates the gamma characteristic (i.e., display gamma) of thedisplay apparatus. FIG. 3D illustrates a gradation characteristic of theentire video processing system constituted by the imaging apparatus andthe display apparatus.

In FIGS. 3A and 3B, a gamma characteristic 907 is a gamma characteristiccorresponding to an input dynamic range “x1”, which is standardizedaccording to ITU-R BT.709. Further, in FIGS. 3A and 3B, a gammacharacteristic 909 is a gamma characteristic corresponding to a larger(widened) input dynamic range “x2” (which is a practical range). Thegamma characteristic 909 is compressed in contrast compared to the gammacharacteristic 907, in the middle-luminance and high-luminance regions.The gamma characteristic 909 can secure a satisfactory output (i.e.,brightness) in the low-luminance and middle-luminance regions (i.e., aregion where human visibility is higher) while expanding the inputdynamic range. In the ordinary imaging mode, the data amount in thehigh-luminance region (i.e., a region where human visibility is lower)is smaller because a reduced allocation is applied to a code ofluminance output value with respect to the number of bits.

When the imaging mode is the ordinary imaging mode, the gamma correctionprocessing unit 109 of the imaging apparatus 100 performs gammacorrection processing in such a way as to convert a code of luminanceinput value of the video signal into a code of output valuecorresponding to a gamma correction curve of the gamma characteristic909. Hereinafter, the code of input value is referred to as “input codevalue” and the code of output value is referred to as “output codevalue.” The video signal having been subjected to the gradationcorrection processing in the ordinary imaging mode can be, for example,recorded and then reproduced so that a reproduced video can be displayedon the monitor unit (e.g., the liquid crystal panel 128) of the displayapparatus.

On the other hand, the gamma characteristic of the display apparatus is,for example, a gamma characteristic 910 illustrated in FIG. 3C. Thedisplay apparatus performs gamma correction processing for converting,for example, a luminance input code value of a recorded and thenreproduced video signal into a luminance value corresponding to a gammacorrection curve of the gamma characteristic 910 illustrated in FIG. 3C.The gamma characteristic 910 illustrated in FIG. 3C is a gammacharacteristic corresponding to an inverse characteristic of the gammacharacteristic 907, which is standardized according to ITU-R BT.709.

A gradation characteristic 911 illustrated in FIG. 3D indicates agradation characteristic of the entire video processing systemconstituted by the imaging apparatus and the display apparatus, which isobtainable in this case. More specifically, the gradation characteristic911 of the entire video processing system, which can be obtained whenthe imaging apparatus uses the gamma characteristic 909 and the displayapparatus uses the gamma characteristic 910 to perform the gammacorrection processing, is an unnatural gradation characteristic becausethe contrast in the high-luminance region is excessively compressedcompared to the contrast in the low-luminance region. A video displayedby the monitor unit of the display apparatus becomes unnatural in thiscase, because the displayed video is defective in gradation, color, andsharpness of a real subject.

Hereinafter, gradation correction characteristics in the high-luminancepriority mode will be described in detail below with reference to FIGS.4A to 4D. Each of FIGS. 4A and 4B illustrates the gamma characteristic(i.e., camera gamma) of the imaging apparatus. FIG. 4C illustrates thegamma characteristic (i.e., display gamma) of the display apparatus.FIG. 4D illustrates a gradation characteristic of the entire videoprocessing system constituted by the imaging apparatus and the displayapparatus.

A gamma characteristic 137 illustrated in FIG. 4A is a gammacharacteristic corresponding to the input dynamic range x1, which isstandardized according to ITU-R BT.709, similar to the gammacharacteristic 907 illustrated in FIG. 3A. On the other hand, in FIGS.4A and 4B, a gamma characteristic 139 is a gamma characteristiccorresponding to the larger (widened) input dynamic range x2 (i.e., thepractical range). The gamma characteristic 139 is determined from therelationship between the input code and the output code can bemaintained in the same condition as the gamma characteristic 137 and thebit allocation rate applied to the code values in a region extendingfrom lower luminance to higher luminance is fixed (not changed).

The present exemplary embodiment uses a function y=f(x) that can expressthe reference gamma characteristic 137 corresponding to the inputdynamic range x1. The input dynamic range is widened “t” times. In thiscase, a function y=f(x/t) can be used to express the gammacharacteristic 139 of the high-luminance priority mode. Consequently,the dynamic range x1 of the gamma characteristic 139 of thehigh-luminance priority mode is larger by a factor of t than the dynamicrange x2 of the reference gamma characteristic 137.

In the present exemplary embodiment, the input dynamic range can be setas an appropriate value for each product (the imaging apparatus) or canbe set as an appropriate value for each imaging mode of the product.Further, the input dynamic range can be set adaptively, for example, foreach imaging scene in the same imaging mode.

When the imaging mode is the high-luminance priority mode, the gammacorrection processing unit 109 of the imaging apparatus 100 performsgamma correction processing for converting a luminance input code valueof the video signal into a code value corresponding to a gammacorrection curve of the gamma characteristic 139. The video signalhaving been subjected to the gradation correction processing in thehigh-luminance priority mode can be, for example, recorded and thenreproduced so that a reproduced video can be displayed on the monitorunit (e.g., the liquid crystal panel 128) of the display apparatusaccording to the present exemplary embodiment.

As mentioned above, in the high-luminance priority mode, the imagingapparatus 100 performs gamma correction processing using the gammacharacteristic 139 whose input code value/output code value relationshipaccords with the input code value/output code value relationship of thereferential gamma characteristic 137, while expanding the input dynamicrange in the entire luminance region extending from lower luminance tohigher luminance. Further, in the high-luminance priority mode, theimaging apparatus 100 fixes (does not change) the bit allocation rate ofthe output code value in the entire luminance region extending fromlower luminance to higher luminance. In the high-luminance prioritymode, the imaging apparatus 100 performs gamma correction processingusing the gamma characteristic 139 which is determined so that the inputcode value/output code value relationship can be maintained in the samecondition as the gamma characteristic 137. Therefore, the contrastcompression (performed in the ordinary imaging mode) is not performed inthe high-luminance region.

On the other hand, the gamma characteristic of the display apparatus isa gamma characteristic 140 illustrated in FIG. 4C, which is similar tothe above-mentioned gamma characteristic 910 illustrated in FIG. 3C.Accordingly, the display apparatus performs gamma correction processingfor converting, for example, a luminance input code value of a recordedand then reproduced video signal into a luminance value, based on agamma correction curve of the gamma characteristic 140 illustrated inFIG. 4C.

A gradation characteristic 141 illustrated in FIG. 4D indicates agradation characteristic of the entire video processing systemconstituted by the imaging apparatus and the display apparatus, which isobtainable in this case. More specifically, the gradation characteristic141 of the entire video processing system, which can be obtained whenthe imaging apparatus has performed the gamma correction processingbased on the gamma characteristic 139, is a linear characteristic in theentire luminance region extending from the low-luminance region to thehigh-luminance region. Accordingly, when the imaging apparatus isoperating in the high-luminance priority mode, the video processingsystem can realize a linear gradation characteristic, such as thegradation characteristic 141 illustrated in FIG. 4D. A reproduced videodisplayed on the monitor unit of the display apparatus becomes naturalin gradation, color, and sharpness of a real subject.

<Gradation Correction Processing by Imaging Apparatus>

FIG. 5 is a flowchart illustrating a flow of processing performed by thecamera microcomputer 111, including input dynamic range determination,gamma correction curve determination, metadata recording, and gammacorrection processing control, when the imaging apparatus 100 accordingto the present exemplary embodiment performs an imaging operation andthen performs gradation correction processing.

Each process of the flowchart illustrated in FIG. 5 is implemented bythe camera microcomputer 111 executing a video processing programdedicated to the imaging apparatus according to the present exemplaryembodiment. The video processing program according to the presentexemplary embodiment can be prepared beforehand in a read only memory(ROM) (not illustrated) of the imaging apparatus 100 or can be read froman external storage medium (not illustrated) and loaded into a randomaccess memory (RAM) (not illustrated) of the imaging apparatus. Asanother exemplary embodiment, the video processing program can bedownloaded into the imaging apparatus 100 via an appropriate network(e.g., internet).

The gradation correction processing of the flowchart illustrated in FIG.5 starts, for example, when a user operates the moving image triggerswitch 124 or the still image trigger switch 125 to start an image orvideo capturing operation. If the imaging apparatus 100 starts thegradation correction processing, then in step S101, the cameramicrocomputer 111 determines the input dynamic range. The input dynamicrange determined in this case is a predetermined value having been setbeforehand according to the imaging mode or a value calculated based onluminance information and color information detected by theluminance/color information detection unit 110. After completing theprocessing in step S101, the operation of the camera microcomputer 111proceeds to step S102.

In step S102, the camera microcomputer 111 performs an exposure control,which includes controlling the above-mentioned diaphragm 102 andcontrolling the shutter speed of the image sensor 105, based on theluminance information and the color information detected by theluminance/color information detection unit 110. After completing theprocessing in step S102, the operation of the camera microcomputer 111proceeds to step S103.

In step S103, the camera microcomputer 111 determines whether thepresent imaging mode is the high-luminance priority mode. In the presentexemplary embodiment, a user can operate the mode dial 126 to select orswitch the imaging mode between the high-luminance priority mode and theordinary imaging mode. If the camera microcomputer 111 determines thatthe present imaging mode is the high-luminance priority mode (YES instep S103), the operation proceeds to step S104. If the cameramicrocomputer 111 determines that the present imaging mode is not thehigh-luminance priority mode (i.e., if the camera microcomputer 111determines that the present imaging mode is the ordinary imaging mode)(NO in step S103), the operation proceeds to step S106.

In step S104, the camera microcomputer 111 determines the gammacorrection curve of the above-mentioned gamma characteristic 139dedicated to the high-luminance priority mode as the gammacharacteristic to be used by the gamma correction processing unit 109 inthe gamma correction processing. After completing the processing in stepS104, the operation of the camera microcomputer 111 proceeds to stepS105.

In step S105, the camera microcomputer 111 generates metadata to bedescribed later that corresponds to the high-luminance priority mode andadds the generated metadata to the video signal. For example, a latterpart of the gamma correction processing unit 109 performs theabove-mentioned processing for adding the metadata, although anexemplary configuration for adding the metadata to the video signal isnot illustrated. The metadata associated with the video signal is thenrecorded in the magnetic tape 115, the DVD disk 117, or the memory card118. After completing the processing in step S105, the operation of thecamera microcomputer 111 proceeds to step S108.

The metadata is, for example, a flag indicating the high-luminancepriority mode, information indicating the input dynamic range,magnification relative to the display luminance reference value and peakluminance value having been set beforehand for the display apparatus,gamma shape information and base gamma about the imaging apparatus. Theinformation indicating the input dynamic range can be used when thedisplay apparatus calculates an appropriate brightness (peak luminancevalue). The magnification relative to the display luminance referencevalue is information corresponding to “t” (in a case where thereferential input dynamic range x1 is widened “t” times) in determiningthe above-mentioned gamma characteristic 139 defined by the functiony=f(x/t) in the high-luminance priority mode. When the referential inputdynamic range x1 is widened “t” times in the high-luminance prioritymode, it is desired that the display luminance of the display apparatusis increased “t” times. Therefore, the information about themagnification is prepared as one of the metadata. Further, the peakluminance value is calculated by the imaging apparatus 100 withreference to a peak luminance value determined, as a standard for thedisplay apparatus, according to ITU-R BT.709. The imaging apparatus 100calculates an appropriate peak luminance value for the display apparatusaccording to the input dynamic range and adds the calculated peakluminance value, as one of the metadata. The gamma shape information isinformation indicating a gamma value representing the shape of the gammacorrection curve. The gamma shape information in the high-luminancepriority mode is information representing the shape of theabove-mentioned gamma characteristic 139. The gamma shape information inthe ordinary imaging mode is information representing the shape of theabove-mentioned gamma characteristic 909. The base gamma is informationindicating the above-mentioned gamma characteristic 137 standardizedaccording to ITU-R BT.709.

On the other hand, when the operation proceeds to step S106, the cameramicrocomputer 111 determines the gamma correction curve of theabove-mentioned gamma characteristic 909 dedicated to the ordinaryimaging mode as the gamma characteristic to be used by the gammacorrection processing unit 109 in the gamma correction processing. Aftercompleting the processing in step S106, the operation of the cameramicrocomputer 111 proceeds to step S107.

In step S107, the camera microcomputer 111 adds metadata correspondingto the ordinary imaging mode to the video signal. The metadata in thiscase is a flag indicating the ordinary imaging mode, informationindicating the input dynamic range, magnification relative to thedisplay luminance reference value and peak luminance value having beenset beforehand for the display apparatus, gamma shape information aboutthe imaging apparatus, and base gamma of the imaging apparatus. Asdescribed above, the latter part of the gamma correction processing unit109 performs the above-mentioned processing for adding the metadata(although not illustrated). The metadata associated with the videosignal is then recorded in the magnetic tape 115, the DVD disk 117, orthe memory card 118. After completing the processing in step S107, theoperation of the camera microcomputer 111 proceeds to step S108.

In step S108, the camera microcomputer 111 causes the gamma correctionprocessing unit 109 to perform the gamma correction processing withreference to the gamma correction curve determined in step S104 or stepS106. After completing the gamma correction processing in step S108, thecamera microcomputer 111 repeats the above-mentioned processing of theflowchart illustrated in FIG. 5 until the power supply to the imagingapparatus 100 is stopped.

<Display Example of Appropriate Exposure Control by Imaging Apparatus>

Hereinafter, an example of an appropriate exposure display, which can beperformed when the display device 116 (e.g., the EVF 123 or the liquidcrystal panel 128) performs a live view display (or a through videodisplay) of a video captured by the imaging apparatus 100 in thehigh-luminance priority mode, will be described in detail below withreference to FIG. 6. FIG. 6 illustrates an example of the live viewvideo displayed by the display device 116 (e.g., the EVF 123 or theliquid crystal panel 128) when the imaging mode is the high-luminancepriority mode.

When an imaging operation is performed, the camera microcomputer 111generates an exposure display signal to display a relationship betweenpresent exposure and appropriate exposure corresponding to the presentvalues with respect to diaphragm, shutter speed, and gain, in anexposure information display area 301 on the screen of the displaydevice 116, as illustrated in FIG. 6. Thus, numerical values indicatingthe diaphragm, the shutter speed, and the gain are displayed in theexposure information display area 301 on the screen of the displaydevice 116. Further, the camera microcomputer 111 updates the contentsdisplayed in the exposure information display area 301 if the diaphragmvalue, the shutter speed, or the gain value is changed by a useroperation. For example, an exposure bar 305 indicating an “under (−)” or“over (+)” state relative to the appropriate exposure (±0) and anexposure mark 304 indicating the present exposure amount are displayedin an exposure display area 303. A user can confirm the “under” or“over” degree of the present exposure relative to the appropriateexposure (±0) by checking the position of the exposure mark 304 on theexposure bar 305.

The gamma characteristic 139 in the high-luminance priority modeaccording to the present exemplary embodiment is a relatively dark gammacharacteristic, compared to the gamma characteristic 909 of the ordinaryimaging mode. Therefore, when the imaging mode is the high-luminancepriority mode, the camera microcomputer 111 displays the displayposition of the appropriate exposure (±0) in the exposure display area303 in such a way as to shift it to a position corresponding to thegamma characteristic 139. Thus, even when a video displayed in thehigh-luminance priority mode is relatively dark compared to that in theordinary imaging mode, a user can determine whether the present exposureis appropriate (=±0) by confirming the display of the exposure displayarea 303.

As mentioned above, according to the present exemplary embodiment, in acase where the imaging apparatus 100 is operating in the high-luminancepriority mode, the video processing system can realize the lineargradation characteristic, such as the gradation characteristic 141illustrated in FIG. 4D. Accordingly, a reproduced video displayed on themonitor unit of the display apparatus becomes natural in gradation,color, and sharpness of a real subject in the entire luminance regionextending from a dark portion (i.e., a low luminance region) to ahighlight portion (i.e., a high-luminance region). In particular, whenthe imaging apparatus 100 is operating in the high-luminance prioritymode, the display apparatus can display a video that is excellent, forexample, in shine of metal, transparency of water, solidity of blue skyand cloud, gradation of skin tone, color reproducibility, and sharpness.

<Configuration of Video Processing System>

FIG. 7 is a block diagram illustrating a schematic configuration of avideo processing system, which includes the above-mentioned imagingapparatus 100 according to the present exemplary embodiment (see FIG. 1)and a display apparatus 220, which is an example of the video processingapparatus according to the present exemplary embodiment.

The imaging apparatus 100 illustrated in FIG. 7 includes constituentcomponents similar to the lens 101 to the DVD disk 117 illustrated inFIG. 1, except for the display device 116 illustrated in FIG. 1.Therefore, redundant description thereof will be avoided. Further, theimaging apparatus 100 illustrated in FIG. 7 is similar to the imagingapparatus 100 illustrated in FIG. 1 in gamma characteristics in theordinary imaging mode and the high-luminance priority mode as well as ingamma correction processing (i.e., gradation correction processing) andtherefore redundant description thereof will be avoided. The signalprocessing unit 112 can record the processed video signal to a computerreadable storage medium, such as the magnetic tape 115, the digitalversatile disk (DVD) disk 117, or the memory card 118.

In the video processing system illustrated in FIG. 7, the displayapparatus 220 receives a video signal having been subjected to thesignal processing from the signal processing unit 112 of the imagingapparatus 100 or a video signal recorded on the magnetic tape 115, theDVD disk 117, or the memory card 118 and then reproduced. The displayapparatus 220 transmits the input video signal to a metadata analysisunit 228 and a signal processing unit 222.

The metadata analysis unit 228 analyzes the above-mentioned metadataadded to the input video signal and transmits metadata analysis resultto a display microcomputer 221. More specifically, the metadata analysisunit 228 transmits the flag indicating the high-luminance priority mode,information indicating the input dynamic range, magnification relativeto the display luminance reference value and peak luminance value,together with the gamma shape information and the base gamma informationabout the imaging apparatus to the display microcomputer 221. Themetadata may not include all of the above-mentioned information, but themetadata analysis unit 228 transmits the entire information analyzedfrom the metadata to the display microcomputer 221. The displaymicrocomputer 221 is an example of a control unit provided in thedisplay apparatus 220. The display microcomputer 221 controls eachsignal process performed in the signal processing unit 222, based on themetadata analysis result.

The signal processing unit 222 according to the present exemplaryembodiment includes at least a gamma correction processing unit 226.According to the example illustrated in FIG. 7, the signal processingunit 222 includes an image-quality mode setting unit 223, a peakluminance setting unit 224, a color correction processing unit 225, anda high-luminance adaptive processing unit 227, in addition to the gammacorrection processing unit 226. The signal processing unit 222 mayinclude all of the image-quality mode setting unit 223, the peakluminance setting unit 224, the color correction processing unit 225,and the high-luminance adaptive processing unit 227, or may include onlyone of them. The video signal having been subjected to the signalprocessing performed by the signal processing unit 222 can betransmitted to and displayed by a display device (i.e., the displaydevice 116 illustrated in FIG. 1), although not illustrated in FIG. 7.

The image-quality mode setting unit 223 sets an image quality mode ofthe display apparatus 220. The display apparatus 220 can perform anappropriate display, for example, for each of various image qualitymodes, such as “entrustment”, “standard”, “vivid”, “dynamic”, “cinema”,and “game” modes. The image-quality mode setting unit 223 performssettings for each image quality mode. For example, the image-qualitymode setting unit 223 sets an image quality mode according to a userselection on an image-quality mode setting menu, or sets an imagequality mode according to the high-luminance priority mode or theordinary imaging mode used by the imaging apparatus 100. As an exemplarysetting of the image quality mode, the image-quality mode setting unit223 sets the image-quality mode “vivid” or “dynamic” when the used modeis the high-luminance priority mode and sets the image-quality mode“standard” when the used mode is the ordinary imaging mode.

The peak luminance setting unit 224 sets a peak luminance value when thedisplay apparatus 220 displays a video on the display device (116). Whenthe imaging apparatus 100 performs the gamma correction processing inthe high-luminance priority mode, the peak luminance setting unit 224performs processing for setting the peak luminance value of the videosignal to an appropriate peak luminance value so that the brightness ofthe video in the low/middle-luminance region becomes equal to thecorresponding brightness in the ordinary imaging mode. The peakluminance value to be set by the peak luminance setting unit 224 may bea regular peak luminance value determined beforehand. However, toreproduce the natural gradation of a real subject, it is desired to setthe peak luminance value in such a manner that the brightness in thehigh-luminance priority mode becomes equal to the correspondingbrightness in the ordinary imaging mode in the low/middle-luminanceregion. Further, when the imaging apparatus 100 performs the gradationcorrection processing in the ordinary imaging mode, the peak luminancesetting unit 224 sets the peak luminance value of the video signal to apredetermined ordinary video-oriented peak luminance value. The peakluminance value setting processing will be described in detail belowwith reference to a flowchart illustrated in FIG. 8.

The color correction processing unit 225 performs color conversionprocessing and specific color correction processing on the video signalbased on matrix calculation or lookup table, although details of thecolor conversion processing and the specific color correction processingare not described in detail below.

The gamma correction processing unit 226 performs gamma correctionprocessing on the video signal. When the imaging apparatus 100 performsthe gradation correction processing in the high-luminance priority mode,the gamma correction processing unit 226 performs gamma correctionprocessing on the video signal with a gamma correction curve that issimilar to an inverse characteristic of the gamma characteristic 139used by the imaging apparatus 100 in the high-luminance priority mode.The gamma characteristic to be used by the gamma correction processingunit 226 may be a regular gamma characteristic standardized according toITU-R BT.709. However, to reproduce the natural gradation of a realsubject, it is desired to use the gamma characteristic corresponding tothe inverse characteristic of the gamma characteristic 139 in thehigh-luminance priority mode. Further, when the imaging apparatus 100performs the gradation correction processing in the ordinary imagingmode, the gamma correction processing unit 226 performs gamma correctionprocessing on the video signal with a gamma correction curve that issimilar to an inverse characteristic of the gamma characteristic 909used by the imaging apparatus 100 in the ordinary imaging mode. Thegamma correction processing will be described in detail below withreference to a flowchart illustrated in FIG. 9.

The high-luminance adaptive processing unit 227 performs adaptiveprocessing on the video signal according to the imaging mode (i.e., thehigh-luminance priority mode or the ordinary imaging mode) of theimaging apparatus 100 having been set in the gradation correctionprocessing. In the present exemplary embodiment, an example of theadaptive processing is dynamic range remaster processing in which thedisplay apparatus 220 restores color information that suits thehigh-luminance region for the video signal whose contrast has beencompressed in the high-luminance region through the gamma correctionprocessing in the ordinary imaging mode. The dynamic range remasterprocessing is determined by expanding the color information in such away as to suit an expansion rate of the luminance to be restored in acase where the high-luminance region entirely turns into white if thedynamic range is expanded in the high-luminance region. As an example ofthe adaptive processing, when the imaging apparatus 100 performs thegradation correction processing in the ordinary imaging mode, thehigh-luminance adaptive processing unit 227 performs the dynamic rangeremaster processing on the video signal in such a way as to restore thecolor information that suits the high-luminance region. On the otherhand, when the imaging apparatus 100 performs the gradation correctionprocessing in the high-luminance priority mode, the high-luminanceadaptive processing unit 227 does not perform the dynamic range remasterprocessing on the video signal.

<Peak Luminance Value Setting Processing by Display Apparatus>

FIG. 8 is a flowchart illustrating exemplary processing performed by thedisplay apparatus 220 to set the brightness of a display video with apeak luminance value that reflects the difference in imaging mode (i.e.,the high-luminance priority mode or the ordinary imaging mode) when thevideo signal is subjected to the gradation correction processing in theimaging apparatus 100. In the present exemplary embodiment, the displayapparatus 220 may be configured to perform only one or both of theprocessing illustrated in FIG. 8 and the processing illustrated in FIG.9. Further, the display apparatus 220 may perform processing of aflowchart illustrated in FIG. 10. Therefore, in the present exemplaryembodiment, each of the flowcharts illustrated in FIGS. 8 to 10 will bedescribed independently.

Each process of the flowchart illustrated in FIG. 8 is implemented bythe display microcomputer 221 executing a video processing programdedicated to the display apparatus according to the present exemplaryembodiment. The video processing program according to the presentexemplary embodiment may be prepared beforehand in a ROM (notillustrated) of the display apparatus 220 or may be read from anexternal storage medium (not illustrated) and loaded into a RAM (notillustrated) of the display apparatus 220. As another exemplaryembodiment, the video processing program may be downloaded into thedisplay apparatus 220 via an appropriate network (e.g., internet).

The processing of the flowchart illustrated in FIG. 8 starts, forexample, when a user operates the mode dial 126 of the video camera 120illustrated in FIG. 2 to select the reproduction mode and operates theoperation switch group 127 to start reproduction. If the processing ofthe flowchart illustrated in FIG. 8 starts, then in step S201, thedisplay microcomputer 221 determines whether the video signal is asignal having been subjected to the gradation correction processing inthe high-luminance priority mode with reference to the flag indicatingthe high-luminance priority mode (i.e., the metadata analysis result) ora user operation. If the display microcomputer 221 determines that thehigh-luminance priority mode flag is present (YES in step S201), theoperation proceeds to step S202. On the other hand, if the displaymicrocomputer 221 determines that the high-luminance priority mode flagis not present, namely, when the video signal is the signal having beensubjected to the gradation correction processing in the ordinary imagingmode (NO in step S201), the operation proceeds to step S203.

When the operation proceeds to step S202, the display microcomputer 221calculates a peak luminance value that equalizes the brightness of thevideo in a low/middle-luminance region with the corresponding brightnessin the ordinary imaging mode. The display microcomputer 221 refers tothe above-mentioned input dynamic range, the magnification relative tothe display luminance reference value, or the peak luminance value(i.e., a part of the metadata) in calculating the peak luminance valuethat equalizes the brightness of the video in the low/middle-luminanceregion with the corresponding brightness in the ordinary imaging mode.

The input dynamic range is the metadata to be used when the cameramicrocomputer 111 of the imaging apparatus 100 calculates the peakluminance value, as mentioned above. Thus, the display microcomputer 221of the display apparatus 220 can obtain the peak luminance value fromthe input dynamic range, similar to the processing performed by thecamera microcomputer 111. Further, the magnification relative to thedisplay luminance reference value is the metadata indicating a valuecalculated by the camera microcomputer 111 of the imaging apparatus 100as display luminance magnification that is appropriate for the displayapparatus when the imaging mode is the high-luminance priority mode, asmentioned above. Thus, the display microcomputer 221 of the displayapparatus 220 can obtain a display luminance (i.e., a peak luminancevalue) that is appropriate for the video signal subjected to thegradation correction processing in the high-luminance priority mode,from the magnification relative to the display luminance referencevalue, in a manner opposite to that in the camera microcomputer 111.Further, the peak luminance value is the metadata indicating a valuecalculated by the camera microcomputer 111 of the imaging apparatus 100with reference to a standard peak luminance value determined for thedisplay apparatus, which is standardized according to ITU-R BT.709, asmentioned above. Thus, the display microcomputer 221 of the displayapparatus 220 can obtain an appropriate peak luminance value for thevideo signal subjected to the gradation correction processing in thehigh-luminance priority mode, with reference to the peak luminance valueincluded in the metadata. As another exemplary embodiment, the displaymicrocomputer 221 may use a predetermined high-luminance priorityvideo-oriented peak luminance value in step S202, instead of referringto the metadata. After completing the processing in step S202, theoperation of the display microcomputer 221 proceeds to step S204.

On the other hand, when the operation proceeds to step S203, the displaymicrocomputer 221 calculates a predetermined ordinary video-orientedpeak luminance value, although processing for calculating thepredetermined ordinary video-oriented peak luminance value is notdescribed. After completing the processing in step S202, the operationof the display microcomputer 221 proceeds to step S204.

When the operation proceeds to step S204, the display microcomputer 221causes the peak luminance setting unit 224 to perform peak luminancevalue setting processing for the display device (116) based on the peakluminance value determined in step S202 or step S203. Thus, when theimaging apparatus 100 performs the gradation correction processing inthe high-luminance priority mode, the peak luminance setting unit 224performs peak luminance value setting processing on the video signal insuch a manner that the brightness of the video in thelow/middle-luminance region becomes equal to the correspondingbrightness in the ordinary imaging mode. On the other hand, when theimaging apparatus 100 performs the gradation correction processing inthe ordinary imaging mode, the peak luminance setting unit 224 performsordinary imaging mode video-oriented peak luminance value settingprocessing on the video signal. After completing the processing in stepS204, the display microcomputer 221 repeats the processing of theflowchart illustrated in FIG. 8 until the power supply to the displayapparatus 220 is stopped.

The display apparatus 220 according to the present exemplary embodimentperforms the peak luminance value setting processing for the displaydevice (116) in conjunction with the gradation correction processingperformed by the imaging apparatus 100 in the high-luminance prioritymode or the ordinary imaging mode. When the imaging apparatus 100 hasperformed the gradation correction processing in the high-luminancepriority mode, the display apparatus 220 equalizes the brightness of thegradation correction processed video signal in the low/middle luminanceregion with the corresponding brightness in the ordinary imaging mode.Thus, the display apparatus 220 can prevent the display video in thelow/middle luminance region from being darkened when the imagingapparatus 100 has performed the gradation correction processing in thehigh-luminance priority mode. Further, in the present exemplaryembodiment, by setting the peak luminance value in such a way as tocompensate the brightness in the low/middle luminance region when theimaging apparatus 100 performs the gradation correction processing inthe high-luminance priority mode, it is feasible to keep balance betweenthe image quality in the high-luminance region having been improved byselecting the high-luminance priority mode and the image quality in thelow/middle luminance.

<Gamma Correction Processing by Display Apparatus>

FIG. 9 is a flowchart illustrating exemplary processing performed by thedisplay apparatus 220 to perform gamma correction processing on adisplay video signal with a gamma correction curve that reflects thedifference in imaging mode (i.e., the high-luminance priority mode orthe ordinary imaging mode) when the video signal has been subjected tothe gradation correction processing in the imaging apparatus 100.

Each process of the flowchart illustrated in FIG. 9 is implemented bythe display microcomputer 221 executing a video processing programdedicated to the display apparatus according to the present exemplaryembodiment. The video processing program according to the presentexemplary embodiment may be prepared beforehand in the ROM (notillustrated) of the display apparatus 220 or may be read from anexternal storage medium (not illustrated) and loaded into the RAM (notillustrated) of the display apparatus 220. As another exemplaryembodiment, the video processing program may be downloaded into thedisplay apparatus 220 via an appropriate network (e.g., internet).

The processing of the flowchart illustrated in FIG. 9 starts, forexample, when a user operates the mode dial 126 of the video camera 120illustrated in FIG. 2 to select the reproduction mode and operates theoperation switch group 127 to start reproduction. If the processing ofthe flowchart illustrated in FIG. 9 starts, then in step S301, thedisplay microcomputer 221 determines whether the video signal is asignal having been subjected to the gradation correction processing inthe high-luminance priority mode with reference to the flag indicatingthe high-luminance priority mode (i.e., the metadata analysis result) ora user operation. If the display microcomputer 221 determines that thehigh-luminance priority mode flag is present (YES in step S301), theoperation proceeds to step S302. On the other hand, if the displaymicrocomputer 221 determines that the high-luminance priority mode flagis not present, namely, when the video signal is the signal having beensubjected to the gradation correction processing in the ordinary imagingmode, (NO in step S301), the operation proceeds to step S303.

When the operation proceeds to step S302, the display microcomputer 221determines a gamma correction curve based on metadata gamma shapeinformation and base gamma information in such a way as to bring thegamma characteristic of the display apparatus 220 most close to aninverse characteristic of the gamma characteristic of the imagingapparatus 100. As another exemplary embodiment, the displaymicrocomputer 221 may be configured to use a predeterminedhigh-luminance priority video-oriented gamma correction curve, insteadof using the metadata gamma shape information and the base gammainformation, in step S302. After completing the processing in step S302,the operation of the display microcomputer 221 proceeds to step S304.

On the other hand, when the operation proceeds to step S303, the displaymicrocomputer 221 determines a predetermined ordinary video-orientedgamma correction curve. After completing the processing in step S302,the operation of the display microcomputer 221 proceeds to step S304.

In step S304, the display microcomputer 221 causes the gamma correctionprocessing unit 226 to perform gamma correction processing based on thegamma correction curve determined in step S302 or step S303. Thus, whenthe imaging apparatus 100 performs the gradation correction processingin the high-luminance priority mode, the gamma correction processingunit 226 performs gamma correction processing on the video signal withthe gamma correction curve that is similar to the inverse characteristicof the gamma characteristic in the high-luminance priority mode. On theother hand, when the imaging apparatus 100 performs the gradationcorrection processing in the ordinary imaging mode, the gamma correctionprocessing unit 226 performs gamma correction processing on the videosignal with the gamma correction curve that is similar to the inversecharacteristic of the gamma characteristic in the ordinary imaging mode.After completing the processing in step S304, the display microcomputer221 repeats the processing of the flowchart illustrated in FIG. 9 untilthe power supply to the display apparatus 220 is stopped.

The display apparatus 220 according to the present exemplary embodimentperforms gamma correction processing with the gamma correction curvethat is similar to the inverse characteristic of the gammacharacteristic used by the imaging apparatus 100 to perform the gammacorrection processing in the high-luminance priority mode or theordinary imaging mode. The display apparatus 220 can improve thegradation characteristic of the entire video processing system inlinearity accuracy, by switching the gamma characteristic to be used inthe gamma correction processing according to the imaging mode (i.e., thehigh-luminance priority mode or the ordinary imaging mode) having beenset in the imaging apparatus 100. For example, when the imagingapparatus 100 has performed the gradation correction processing in thehigh-luminance priority mode, the contrast compression (performed in theordinary imaging mode) is not performed even if the input dynamic rangeis expanded, and adequate luminance linearity in the gradationcharacteristic of the entire video processing system can be obtained.Thus, it becomes feasible to realize natural gradation in the entireregion extending from the dark portion to the highlight portion.

<Signal Processing by Display Apparatus>

FIG. 10 is a flowchart illustrating exemplary processing performed bythe display microcomputer 221 and the signal processing unit 222 in thedisplay apparatus 220.

Each process of the flowchart illustrated in FIG. 10 is implemented bythe display microcomputer 221 executing a video processing programdedicated to the display apparatus according to the present exemplaryembodiment. The video processing program according to the presentexemplary embodiment may be prepared beforehand in the ROM (notillustrated) of the display apparatus 220 or may be read from anexternal storage medium (not illustrated) and loaded into the RAM, ormay be downloaded via an appropriate network.

The processing of the flowchart illustrated in FIG. 10 starts, forexample, when a user operates the mode dial 126 of the video camera 120to select the reproduction mode and operates the operation switch group127 to start reproduction. If the processing of the flowchartillustrated in FIG. 10 starts, then in step S401, the displaymicrocomputer 221 determines whether the video signal is a signal havingbeen subjected to the gradation correction processing in thehigh-luminance priority mode with reference to the flag indicating thehigh-luminance priority mode (i.e., the metadata analysis result) or auser operation. If the display microcomputer 221 determines that thehigh-luminance priority mode flag is present (YES in step S401), theoperation proceeds to step S402. On the other hand, if the displaymicrocomputer 221 determines that the high-luminance priority mode flagis not present (NO in step S401), the operation proceeds to step S406.

When the operation proceeds to step S402, the display microcomputer 221determines an image quality mode according to a user selection on theimage-quality mode setting menu or an image quality mode suitable forthe high-luminance priority mode. After completing the processing instep S402, the operation of the display microcomputer 221 proceeds tostep S403. On the other hand, when the operation proceeds to step S406,the display microcomputer 221 determines an image quality mode accordingto a user selection on the image-quality mode setting menu or an imagequality mode suitable for the ordinary imaging mode. Then, the displaymicrocomputer 221 causes the image-quality mode setting unit 223 toperform image-quality mode setting processing according to thedetermined image quality mode. After completing the processing in stepS406, the operation of the display microcomputer 221 proceeds to stepS407.

When the operation proceeds to step S403, the display microcomputer 221calculates a peak luminance value that equalizes the brightness of thevideo in the low/middle-luminance region with the correspondingbrightness in the ordinary imaging mode, similar to the above-mentionedprocessing in step S202 illustrated in FIG. 8. After completing theprocessing in step S403, the operation of the display microcomputer 221proceeds to step S404. On the other hand, when the operation proceeds tostep S407, the display microcomputer 221 calculates a predeterminedordinary video-oriented peak luminance value, similar to theabove-mentioned processing in step S203 illustrated in FIG. 8. Aftercompleting the processing in step S407, the operation of the displaymicrocomputer 221 proceeds to step S408.

When the operation proceeds to step S404, the display microcomputer 221determines a gamma correction curve that is closest to the inversecharacteristic of the gamma characteristic 139 used by the imagingapparatus 100, similar to the above-mentioned processing in step S302illustrated in the FIG. 9. After completing the processing in step S404,the operation of the display microcomputer 221 proceeds to step S405. Onthe other hand, when the operation proceeds to step S408, the displaymicrocomputer 221 determines a predetermined ordinary video-orientedgamma correction curve, similar to the above-mentioned processing instep S303 illustrated in FIG. 9. After completing the processing in stepS408, the operation of the display microcomputer 221 proceeds to stepS409.

When the operation proceeds to step S405, the display microcomputer 221determines adaptive processing to be applied to the video signal havingbeen subjected to the gradation correction processing performed by theimaging apparatus 100 in the high-luminance priority mode. In otherwords, the display microcomputer 221 determines whether to perform theadaptive processing. After completing the processing in step S405, theoperation of the display microcomputer 221 proceeds to step S410. On theother hand, when the operation proceeds to step S409, the displaymicrocomputer 221 determines adaptive processing to be applied to thevideo signal having been subjected to the gradation correctionprocessing performed by the imaging apparatus 100 in the ordinaryimaging mode. After completing the processing in step S409, theoperation of the display microcomputer 221 proceeds to step S410.

In step S410, the display microcomputer 221 causes the image-qualitymode setting unit 223 to perform image-quality mode setting processingas mentioned above, in such a way as to set the image quality modedetermined in step S405 or step S406. After completing the processing instep S410, the operation of the display microcomputer 221 proceeds tostep S411.

In step S411, the display microcomputer 221 causes the peak luminancesetting unit 224 to perform peak luminance value setting processingbased on the peak luminance value determined in step S403 or step S407,similar to the above-mentioned processing in step S204 illustrated inthe FIG. 8. After completing the processing in step S411, the operationof the display microcomputer 221 proceeds to step S412.

In step S412, the display microcomputer 221 causes the gamma correctionprocessing unit 226 to perform gamma correction processing based on thegamma correction curve determined in step S404 or step S408, similar tothe above-mentioned processing in step S304 illustrated in FIG. 9. Aftercompleting the processing in step S412, the operation of the displaymicrocomputer 221 proceeds to step S413.

In step S413, the display microcomputer 221 causes the high-luminanceadaptive processing unit 227 to perform adaptive processing as mentionedabove based on the adaptive processing determined in step S405 or stepS409. After completing the processing in step S413, the displaymicrocomputer 221 repeats the processing of the flowchart illustrated inFIG. 10 until the power supply to the display apparatus 220 is stopped.

As mentioned above, according to the video processing system includingthe imaging apparatus 100 and the display apparatus 220 according to thepresent exemplary embodiment, it is feasible to reproduce naturalgradation, color, and sharpness similar to the gradation characteristicof a real subject in the entire luminance region extending from lowerluminance to higher luminance, while securing a practical input dynamicrange.

As an example, exemplary processing for realizing the present inventionincludes supplying a program capable of realizing at least one of thefunctions described in the above-mentioned exemplary embodiments to asystem or an apparatus via a network or an appropriate storage mediumand causing at least one processor of a computer provided in the systemor the apparatus to read and execute the program. Further, anappropriate circuit (e.g., ASIC) capable of realizing at least one ofthe above-mentioned functions is employable to realize the presentinvention.

The above-mentioned exemplary embodiments are mere examples capable ofembodying the present invention and should not be referred to for thepurpose of narrowly interpreting the technical range of the presentinvention. The present invention can be changed or modified in variousways without departing from the technical ideas or essential features ofthe invention.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2015-214554, filed Oct. 30, 2015, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A video processing apparatus comprising: at leastone processor and/or circuit configured to function as following units,a control unit configured to set a gamma characteristic for a seconddynamic range larger than a first dynamic range, based on a referentialgamma characteristic in which a relationship between a luminance inputvalue and a luminance output value is predetermined in the entireluminance range of the first dynamic range; and a correction unitconfigured to perform gamma correction processing on a video signalhaving the second dynamic range by using the set gamma characteristic,wherein in a case where the correction unit performs the gammacorrection processing based on the set gamma characteristic, a code ofthe input value, which is obtained by coding each luminance value of thecaptured video signal, is converted into a code of the output value,while a bit allocation rate of the output value code in an entireluminance region extending from lower luminance to higher luminance isnot changed with respect to the referential gamma characteristic.
 2. Thevideo processing apparatus according to claim 1, wherein the gammacharacteristic to be set by the control unit is a gamma characteristicof the second dynamic range that is larger by a predeterminedmagnification compared to the first dynamic range of the referentialgamma characteristic.
 3. The video processing apparatus according toclaim 1, wherein the control unit is configured to add to the videosignal having been subjected to the gamma correction processing, atleast one of: information indicating which of the first gammacharacteristic and the second gamma characteristic has been used in thegamma correction processing, information corresponding to apredetermined magnification in a case where the selected first or secondgamma characteristic is a gamma characteristic of the second dynamicrange that is larger by the predetermined magnification compared to thefirst dynamic range of the referential gamma characteristic, informationrepresenting a peak luminance value of the video signal, gamma shapeinformation of the selected first or second gamma characteristic, andinformation indicating the referential gamma characteristic, asmetadata.
 4. The video processing apparatus according to claim 1,further comprising a signal processing unit configured to output thevideo signal to a display or a computer readable storage medium.
 5. Avideo processing method, comprising: setting a gamma characteristic fora second dynamic range larger than a first dynamic range, based on areferential gamma characteristic in which a relationship between aluminance input value and a luminance output value is predetermined inthe entire luminance range of the first dynamic range; and performinggamma correction processing on a video signal having the second dynamicrange by using the set gamma characteristic, wherein in a case where thegamma correction processing is performed based on the set gammacharacteristic, a code of the input value, which is obtained by codingeach luminance value of the captured video signal, is converted into acode of the output value, while a bit allocation rate of the outputvalue code in an entire luminance region extending from lower luminanceto higher luminance is not changed with respect to the referential gammacharacteristic.
 6. A non-transitory computer readable medium storing aprogram that, when implemented by a video processing apparatus, causesthe video processing apparatus to perform the method according to claim5.
 7. A video processing apparatus comprising: at least one processorand/or circuit configured to function as following units, a control unitconfigured to set a gamma characteristic for a second dynamic rangelarger than a first dynamic range, based on a referential gammacharacteristic in which a relationship between a luminance input valueand a luminance output value is predetermined in the entire luminancerange of the first dynamic range; a correction unit configured toperform gamma correction processing on a video signal having the seconddynamic range by using the set gamma characteristic; and wherein thecontrol unit is configured to select, according to a mode of theapparatus, one of: a first gamma characteristic, which is set accordingto the relationship between the input luminance value and the outputluminance value of the referential gamma characteristic; and a secondgamma characteristic, which is set by compressing an output luminancevalue relative to an input luminance value in a high-luminance region,compared to the relationship between the input luminance value and theoutput luminance value of the referential gamma characteristic; whereinthe correction unit performs the gamma correction processing by usingthe first gamma characteristic or the second gamma characteristicselected according to the mode of the apparatus, wherein the controlunit is configured to generate an exposure display signal to display arelationship between present exposure and appropriate exposure, as apositional relationship, when a live view display is performed byperforming the gamma correction processing on a captured video signal,and wherein, in a case where the gamma correction processing isperformed by using the first gamma characteristic, the control unitgenerates the exposure display signal in such a way as to set a positionindicating the appropriate exposure based on luminance when the gammacorrection processing is performed by using the first gammacharacteristic.
 8. A method for a video processing apparatus comprising:setting a gamma characteristic for a second dynamic range larger than afirst dynamic range, based on a referential gamma characteristic inwhich a relationship between a luminance input value and a luminanceoutput value is predetermined in entire luminance range of the firstdynamic range; performing gamma correction processing on a video signalhaving the second dynamic range by using the set gamma characteristic;and wherein setting the gamma characteristic comprises selecting,according to a mode of the apparatus, one of: a first gammacharacteristic, which is set according to the relationship between theinput luminance value and the output luminance value of the referentialgamma characteristic; and a second gamma characteristic, which is set bycompressing an output luminance value relative to an input luminancevalue in a high-luminance region, compared to the relationship betweenthe input luminance value and the output luminance value of thereferential gamma characteristic; wherein performing the gammacorrection processing comprises performing the gamma correctionprocessing by using the first gamma characteristic or the second gammacharacteristic selected according to the mode of the apparatus, whereinsetting the gamma characteristic comprises generating an exposuredisplay signal to display a relationship between present exposure andappropriate exposure, as a positional relationship, when a live viewdisplay is performed by performing the gamma correction processing on acaptured video signal, and wherein, in a case where the gamma correctionprocessing is performed by using the first gamma characteristic, settingthe gamma characteristic comprises generating the exposure displaysignal in such a way as to set a position indicating the appropriateexposure based on luminance when the gamma correction processing isperformed by using the first gamma characteristic.